In numbers.c in libxslt 1.1.33, an xsl:number with certain format strings could lead to a uninitialized read in xsltNumberFormatInsertNumbers. This could allow an attacker to discern whether a byte on the stack contains the characters A, a, I, i, or 0, or any other character.
https://www.oracle.com/security-alerts/cpujan2020.html
https://usn.ubuntu.com/4164-1/
https://security.netapp.com/advisory/ntap-20200122-0003/
https://security.netapp.com/advisory/ntap-20190806-0004/
https://oss-fuzz.com/testcase-detail/5631739747106816
https://lists.debian.org/debian-lts-announce/2019/07/msg00020.html
https://gitlab.gnome.org/GNOME/libxslt/commit/c5eb6cf3aba0af048596106ed839b4ae17ecbcb1
https://bugs.chromium.org/p/oss-fuzz/issues/detail?id=14471
http://www.openwall.com/lists/oss-security/2019/11/17/2
http://lists.opensuse.org/opensuse-security-announce/2020-05/msg00062.html